Leveling in Ninja.io can be split into 2 categories: skill levels and experience levels.
Skill is roughly calculated as follows:
skill = kd_ratio * quality * activity
kd_ratio is kill/death ratio.
quality is determined by average experience obtained from kills. Higher quality indicates more sprees and more kills of players with good ratios themselves.
activity is based on activity over the past 10 days. Having less than 2000 kills over the past 10 days will result in a lower activity value.
A high skill value can be obtained by killing at least 2000 players every 10 days, by making sure that you kill good players and make lots of combos, and by keeping your k/d ratio high.
The following skill titles can be obtained:
Note that flag caps and DM / TDM / CTF / DB wins have no bearing on skill level. These will be displayed & ranked separately in a future update.
Players level according to a point system.
Killing a person who is performing roughly equal will yield 100 points. Killing an inactive guest or a guest with no kills will yield no more than 1 point. A kill can yield no more than 200 points, however sprees (double kills and triple kills) multiply the amount of points.
The maximum attainable level is be 160. It requires on average 64.000 kills of equally performing players to reach the highest level.
Every 16 levels, you get a new shuriken (note that these are not the same shurikens that you use to fight ingame):